Incomplete trisomy 22

Schinzel, Albert; Schmid, Werner; Maur, P. Auf der; Moser, Hans; Degenhardt, K; Geisler, M.; Grubisic, A.

doi:10.1007/bf00274675

Cited by 52 publications

(20 citation statements)

References 33 publications

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“…The chromosome 22q11 region is susceptible to rearrangements associated with congenital anomaly disorders, including velocardiofacial syndrome/DiGeorge syndrome (VCFS/DGS [MIM 192430/MIM 188400]; DiGeorge 1965;Shprintzen et al 1978), cat-eye syndrome (CES [MIM 115470]; Guanti et al 1981;Reiss et al 1985) and der(22) syndrome (Fraccaro et al 1980;Zackai and Emanuel 1980;Schinzel et al 1981). Most patients with VCFS/DGS have 3-Mb hemizygous deletions of 22q11; a subset have a nested distal deletion endpoint, resulting in a 1.5-Mb deletion, and a few rare patients have unique deletions (Lindsay et al 1995;Morrow et al 1995;Carlson et al 1997).…”

Section: Introductionmentioning

confidence: 99%

AT-Rich Palindromes Mediate the Constitutional t(11;22) Translocation

Edelmann

Spiteri

Koren

et al. 2001

The American Journal of Human Genetics

172

120

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The constitutional t(11;22) translocation is the only known recurrent non-Robertsonian translocation in humans. Offspring are susceptible to der(22) syndrome, a severe congenital anomaly disorder caused by 3&rcolon;1 meiotic nondisjunction events. We previously localized the t(11;22) translocation breakpoint to a region on 22q11 within a low-copy repeat termed "LCR22" and within an AT-rich repeat on 11q23. The LCR22s are implicated in mediating different rearrangements on 22q11, leading to velocardiofacial syndrome/DiGeorge syndrome and cat-eye syndrome by homologous recombination mechanisms. The LCR22s contain AT-rich repetitive sequences, suggesting that such repeats may mediate the t(11;22) translocation. To determine the molecular basis of the translocation, we cloned and sequenced the t(11;22) breakpoint in the derivative 11 and 22 chromosomes in 13 unrelated carriers, including two de novo cases and der(22) syndrome offspring. We found that, in all cases examined, the reciprocal exchange occurred between similar AT-rich repeats on both chromosomes 11q23 and 22q11. To understand the mechanism, we examined the sequence of the breakpoint intervals in the derivative chromosomes and compared this with the deduced normal chromosomal sequence. A palindromic AT-rich sequence with a near-perfect hairpin could form, by intrastrand base-pairing, on the parental chromosomes. The sequence of the breakpoint junction in both derivatives indicates that the exchange events occurred at the center of symmetry of the palindromes, and this resulted in small, overlapping staggered deletions in this region among the different carriers. On the basis of previous studies performed in diverse organisms, we hypothesize that double-strand breaks may occur in the center of the palindrome, the tip of the putative hairpin, leading to illegitimate recombination events between similar AT-rich sequences on chromosomes 11 and 22, resulting in deletions and loss of the palindrome, which then could stabilize the DNA structure.

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Section: Introductionmentioning

confidence: 99%

AT-Rich Palindromes Mediate the Constitutional t(11;22) Translocation

Edelmann

Spiteri

Koren

et al. 2001

The American Journal of Human Genetics

172

120

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“…Only a few patients diagnosed with CES have been reported as suffering from a severe developmental delay. These patients did not carry the common type 1 sSMC but carried other chromosomal anomalies rarely reported to be associated with the CES phenotype: partial trisomy 22q (more often associated with severe ID/DD [ 6 , 7 ]) or a type 2 sSMC [ 8 ]. It is noteworthy that none of these patients have been assessed with array-CGH; hence, the presence of an additional, small, associated chromosomal imbalance (which may have been involved in the severe neurological phenotype) cannot be ruled out.…”

Section: Discussionmentioning

confidence: 99%

Severe Psychomotor Delay in a Severe Presentation of Cat-Eye Syndrome

Jedraszak¹,

Receveur

Andrieux

et al. 2015

Case Reports in Genetics

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Cat-eye syndrome is a rare genetic syndrome of chromosomal origin. Individuals with cat-eye syndrome are characterized by the presence of preauricular pits and/or tags, anal atresia, and iris coloboma. Many reported cases also presented with variable congenital anomalies and intellectual disability. Most patients diagnosed with CES carry a small supernumerary bisatellited marker chromosome, resulting in partial tetrasomy of 22p-22q11.21. There are two types of small supernumerary marker chromosome, depending on the breakpoint site. In a very small proportion of cases, other cytogenetic anomalies are reportedly associated with the cat-eye syndrome phenotype. Here, we report a patient with cat-eye syndrome caused by a type 1 small supernumerary marker chromosome. The phenotype was atypical and included a severe developmental delay. The use of array comparative genomic hybridization ruled out the involvement of another chromosomal imbalance in the neurological phenotype. In the literature, only a few patients with cat-eye syndrome present with a severe developmental delay, and all of the latter carried an atypical partial trisomy 22 or an uncharacterized small supernumerary marker chromosome. Hence, this is the first report of a severe neurological phenotype in cat-eye syndrome with a typical type 1 small supernumerary marker chromosome. Our observation clearly complicates prognostic assessment, particularly when cat-eye syndrome is diagnosed prenatally.

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“…[ 29 ] Clinically, the features of CES include ocular colobomata, anal atresia, congenital heart defects, renal malformations, craniofacial anomalies (e.g., preauricular skin tags and pits), male genital anomalies, skeletal defects, and borderline to moderate mental retardation. [ 30 ] The SMC derived from chromosome 22 can be different in molecular size, based on the LCRs in the q11 region where the rearrangement occurs. [ 9 10 ] The CES phenotype is variable and no correlation has yet been recognized between CES phenotypes and the supernumerary region.…”

Section: Syndromesmentioning

confidence: 99%

Small supernumerary marker chromosomes and their correlation with specific syndromes

et al. 2015

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A small supernumerary marker chromosome (sSMC) is a structurally abnormal chromosome. It is an additional chromosome smaller than one chromosome most often lacking a distinct banding pattern and is rarely identifiable by conventional banding cytogenetic analysis. The origin and composition of an sSMC is recognizable by molecular cytogenetic analysis. These sSMCs are seen in different shapes, including the ring, centric minute, and inverted duplication shapes. The effects of sSMCs on the phenotype depend on factors such as size, genetic content, and the level of the mosaicism. The presence of an sSMC causes partial tris- or tetrasomy, and 70% of the sSMC carriers are clinically normal, while 30% are abnormal in some way. In 70% of the cases the sSMC is de novo, in 20% it is inherited from the mother, and in 10% it is inherited from the father. An sSMC can be causative for specific syndromes such as Emanuel, Pallister-Killian, or cat eye syndromes. There may be more specific sSMC-related syndromes, which may be identified by further investigation. These 10 syndromes can be useful for genetic counseling after further study.

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Incomplete trisomy 22

Cited by 52 publications

References 33 publications

AT-Rich Palindromes Mediate the Constitutional t(11;22) Translocation

AT-Rich Palindromes Mediate the Constitutional t(11;22) Translocation

Severe Psychomotor Delay in a Severe Presentation of Cat-Eye Syndrome

Small supernumerary marker chromosomes and their correlation with specific syndromes

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